Network device with handover based packet management

ABSTRACT

A network device includes a transceiver and a control module. The transceiver transmits, from the network device to a first access point, first packets and second packets, transmits a request signal to a second access point to perform a handover of support for the network device from the first access point to the second access point, and receives a control message from the second access point based on the request signal. The transceiver receives the control message subsequent to transmitting the first packets to the second access point. The control message indicates the second access point received, during the handover, the first packets from the first access point, and one of the first packets from the network device. The control module, based on the control message, refrains from transmitting the one of the first packets, discards the first packets, and has the second packets transmitted to the second access point.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/267,958, filed Nov. 10, 2008, which claims the benefit of U.S.Provisional Application No. 60/988,589, filed on Nov. 16, 2007. Thedisclosures of the above applications are incorporated herein byreference in their entirety.

FIELD

The present disclosure relates to communication systems, and moreparticularly to protocols for managing handover events.

BACKGROUND

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent the work is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentdisclosure.

In the standardization of evolved 3rd Generation Partnership Project(3GPPTM) networks, 3GPPTM system architecture evolution (SAE) work isdefining a new architecture where both evolved 3GPPTM wireless access(LTE—Long Term Evolution access) and non-3GPPTM accesses are considered.The technical specification (TS) 23.401 “3GPPTM GPRS enhancements forLTE access” [1] and the TS 23.402 “3GPPTM Architecture enhancements fornon-3GPPTM accesses” [2], which are incorporated herein by reference intheir entirety, contain the current definitions for the architecture andrelated mechanisms. Specifically, [1] covers one possible implementationof the SAE network that supports LTE accesses, and [2] describes analternative implementation of the SAE network that supports both LTE andnon-3GPPTM accesses.

In a long-term evolution radio access network (LTE RAN), user datapackets are transmitted and received between user equipment (UE) andbase stations (such as evolved Node-B stations). The user data packetsare transmitted and received using protocol stacks that are associatedwith the UE and the base stations. The protocol stacks each includethree service and function layers L1, L2 and L3. The first layer is thebottom most layer and the third layer is the upper most layer. The L1layer includes a physical layer (PHY). The L2 layer includes a mediumaccess layer (MAC), a radio link control layer (RLC), and a packet dataconvergence layer (PDCP). The L3 layer includes an Internet protocollayer (IP).

During, for example, an uplink from the UE to a first base station BS1,user data packets are transmitted from the UE to the first base stationBS1. When the first base station BS1 successfully receives the user datapackets, the first base station BS1 transmits an acknowledgement signal(ACK) to the UE indicating a successful transmission.

Under certain conditions, the UE may not receive the acknowledgement(ACK) signal and may time out. This may result in the user data packetsbeing discarded by the transmitter of the UE. In a LTE RAN, and withrespect to a real-time application, the transmitter of the UE sets atimer in association with each of the user data packets. Examples ofreal-time applications are voice over Internet phone (VoIP) orstreaming. When the UE does not receive an ACK signal within apredetermined period after transmission of a corresponding user datapacket, the UE times out and discards the user data packet.

During a handover between the first base station BS1 of a first radioaccess network (RAN) and a second base station BS2 of a target RAN,radio communication between the UE and the first base station BS1 maydeteriorate. When a UE is near the outer boundary of the first RAN,radio transmission degrades. As a result of the handover anddeteriorated radio communication, the UE may not receive an ACK signalwith regard to certain transmitted packets. Thus, the UE may retransmitthe packets to the second base station BS2 regardless of whether thefirst base station BS1 successfully received the packets.

SUMMARY

A network device is provided and includes a transceiver and a controlmodule. The transceiver is configured to (i) transmit, from the networkdevice to a first access point, first packets and second packets, (ii)transmit a request signal to a second access point to perform a handoverof support for the network device from the first access point to thesecond access point, and (iii) receive a control message from the secondaccess point based on the request signal. The transceiver is configuredto receive the control message subsequent to transmitting the firstpackets to the second access point. The control message indicates thesecond access point received, during the handover, (i) the first packetsfrom the first access point, and (ii) one of the first packets from thenetwork device. The control module is configured to, based on thecontrol message, (i) refrain from transmitting the one of the firstpackets to the second access point, (ii) discard the first packets, and(iii) transmit the second packets to the second access point via thetransceiver.

In other features, a method is provided and includes transmitting, froma network device to a first access point, first packets and secondpackets. A request signal is transmitted to a second access point toperform a handover of support for the network device from the firstaccess point to the second access point. A control message is receivedfrom the second access point based on the request signal. The controlmessage is received subsequent to the first packets being transmitted tothe second access point. The control message indicates the second accesspoint received, during the handover, (i) the first packets from thefirst access point, and (ii) one of the first packets from the networkdevice. The method further includes, based on the control message,refraining from transmitting the one of the first packets to the secondaccess point, discarding the first packets, and transmitting the secondpackets to the second access point.

In other features, a network device is provided that includes atransceiver that transmits N packets to a first access point and thatreceives a control message from a second access point. The controlmessage indicates reception of one of the N packets by the second accesspoint from the first access point during a handover of the networkdevice from the first access point to the second access point. N is aninteger. A control module causes the transceiver to refrain fromtransmitting the one of the N packets to the second access point basedon the control message. The handover of the network device from thefirst access point to the second access point occurs prior to thecontrol message being received by the transceiver.

In other features, the transceiver transmits the one of the N packets tothe second access point prior to the control message being received bythe transceiver. The control message indicates reception of a redundantpacket by the second access point based on reception of the one of the Npackets by the second access point.

In still other features, the N packets include a first packet and asecond packet. The control message indicates reception of one of thefirst packet and the second packet by the first access point. Thecontrol module causes the transceiver to refrain from transmitting theother one of the first packet and the second packet to the second accesspoint based on the control message.

In other features, the first access point receives the one of the Npackets in a first radio access network and the second access pointreceives the one of the N packets in a second radio access network. Inyet other features, the control message is at least one of initiallygenerated within a packet data convergence protocol layer of the secondaccess point and initially generated as a packet data convergenceprotocol layer control packet data unit.

In other features, the transceiver transmits a first set of service dataunits to the first access point. The first set of service data unitsincludes the N packets. The transceiver transmits a second set ofservice data units to the second access point. The second set of servicedata units includes the one of the N packets.

In still other features, the transceiver receives the control messageprior to transmitting the one of the N packets to the second accesspoint. In other features, the transceiver receives the control messageprior to transmitting the N packets to the second access point. Thecontrol module causes the transceiver to refrain from transmitting the Npackets to the second access point based on the control message.

In other features, the control message indicates reception of M of the Npackets, where M is an integer. The control module causes thetransceiver to refrain from transmitting the M of the N packets to thesecond access point.

In other features, the transceiver transmits the one of the N packets tothe second access point based on reception of an acknowledgement signalfrom the first access point. In other features, the transceiver discardsat least one of the N packets after a predetermined period. In yet otherfeatures, the transceiver transmits the one of the N packets to thesecond access point based on expiration of a predetermined time period.

In other features, a target access point is provided that includes atransceiver that receives one of N packets associated with a servicerequest device. The one of the N packets is received by the transceiverfrom a first access point during a handover of the service requestdevice from the first access point to the target access point. The Npackets are transmitted from the service request device to the firstaccess point and N is an integer. A control module generates a controlmessage. The control message indicates reception of the one of the Npackets by the transceiver. The transceiver transmits the controlmessage to the service request device to prevent the service requestdevice from transmitting the one of the N packets to the target accesspoint.

In other features, the service request device transmits the N packets tothe first access point prior to the handover of the service requestdevice from the first access point to the target access point. In stillother features, the transceiver receives the one of the N packets fromthe service request device prior to the control message beingtransmitted by the transceiver. The control message indicates receptionof a redundant packet by the transceiver based on the reception of theone of the N packets from the service request device.

In yet other features, the N packets include a first packet and a secondpacket. The control message indicates reception of one of the firstpacket and the second packet by the first access point. The controlmodule causes the transceiver to transmit the control message to theservice request device to prevent the service request device fromtransmitting the other one of the first packet and the second packet tothe transceiver based on the control message.

In other features, the first access point receives the one of the Npackets in a first radio access network. The transceiver receives theone of the N packets in a second radio access network. In otherfeatures, the control message is at least one of initially generatedwithin a packet data convergence protocol layer of the transceiver andinitially generated as a packet data convergence protocol layer controlpacket data unit.

In other features, the control message indicates reception of M of the Npackets by the transceiver. M is an integer. The service request devicediscards the M of the N packets based on the control message. In otherfeatures, the transceiver receives the one of the N packets from theservice request device based on reception of an acknowledgement signalby the service request device from the first access point.

In yet other features, the transceiver receives the control messageafter transmitting the one of the N packets to the second access pointand before transmitting N−1 of the N packets to the second access point.In still other features, the transceiver refrains from transmitting apacket of the N packets other than the one of the N packets based on thecontrol message. In other features, the control module causes thetransceiver to discard the M of the N packets based on the controlmessage.

In other features, the transceiver receives the control message in along-term evolution radio access network. In other features, thetransceiver discards at least one of the N packets a predeterminedperiod after from reception of the at least one of the N packets by thetransceiver.

In other features, the transceiver transmits a discard message to thesecond access point. The discard message indicates transmission of atleast one of the N packets to the second access point, discarding of theat least one of the N packets, and adjustment of a message window. Inother features, a network is provided that includes the network deviceand further includes the second access point.

In other features, the control message is initially generated as apacket data convergence protocol layer control packet data unit. Inother features, the transceiver receives a first set of service dataunits from the first access point that include the one of the N packets.The transceiver also receives a second set of service data units fromthe service request device that include the one of the N packets.

In yet other features, the first set of service data units include Xpackets and the second set of service data units includes Y packets. Xand Y are integers and the X packets are independent of the Y packetsother than the inclusion of the one of the N packets.

In other features, the transceiver transmits the control message beforereceiving the one of the N packets from the service request device. Inother features, the transceiver transmits the control message beforereceiving the N packets from the service request device.

In other features, the transceiver transmits the control message afterreceiving the one of the N packets from the service request device andbefore receiving N−1 of the N packets from the service request device.In other features, the transceiver transmits the control message in along-term evolution radio access network.

In still other features, the transceiver discards at least one of the Npackets after a predetermined period. In other features, the transceiverreceives the one of the N packets from the service request device basedon expiration of a predetermined period.

In yet other features, the transceiver receives a discard message fromthe service request device. The discard message indicates transmissionof at least one of the N packets to the transceiver, discarding of theat least one of the N packets by the service request device, andadjustment of a message window. In other features, a network is providedthat includes the target access point and further includes the servicerequest device.

In other features, a method of operating a network device is providedthat includes transmitting N packets to a first access point thatreceives a control message from a second access point via a transceiver.The control message indicates reception of one of the N packets by thesecond access point from the first access point during a handover of thenetwork device from the first access point to the second access point. Nis an integer. The transceiver refrains from transmitting the one of theN packets to the second access point based on the control message. Thehandover of the network device from the first access point to the secondaccess point occurs prior to the control message being received by thetransceiver.

In other features, the one of the N packets is transmitted to the secondaccess point prior to the control message being received by thetransceiver. The control message indicates reception of a redundantpacket by the second access point based on reception of the one of the Npackets by the second access point.

In yet other features, the transceiver refrains from transmitting theother one of the first packet and the second packet to the second accesspoint based on the control message, the N packets include a first packetand a second packet, and the control message indicates reception of oneof the first packet and the second packet by the first access point.

In other features, the first access point receives the one of the Npackets in a first radio access network and the second access pointreceives the one of the N packets in a second radio access network. Instill other features, the control message is at least one of initiallygenerated within a packet data convergence protocol layer of the secondaccess point and initially generated as a packet data convergenceprotocol layer control packet data unit.

In other features, a first set of service data units is transmitted tothe first access point. The first set of service data units includes theN packets. A second set of service data units is transmitted to thesecond access point. The second set of service data units includes theone of the N packets.

In other features, the control message is received by the transceiverprior to transmitting the one of the N packets to the second accesspoint. In other features, the transceiver refrains from transmitting theN packets to the second access point based on the control message. Thetransceiver receives the control message prior to transmitting the Npackets to the second access point.

In yet other features, the transceiver refrains from transmitting the Mof the N packets to the second access point. The control messageindicates reception of M of the N packets. M is an integer.

In other features, the one of the N packets are transmitted to thesecond access point based on reception of an acknowledgement signal fromthe first access point. In other features, at least one of the N packetsis discarded after a predetermined period. In other features, the one ofthe N packets is transmitted to the second access point based onexpiration of a predetermined time period.

In other features, a method of operating a target access point isprovided and includes receiving one of N packets associated with aservice request device via a transceiver. The one of the N packets isreceived by the transceiver from a first access point during a handoverof the service request device from the first access point to the targetaccess point. The N packets are transmitted from the service requestdevice to the first access point and N is an integer. A control messageis generated. The control message indicates reception of the one of theN packets by the transceiver. The control message is transmitted to theservice request device to prevent the service request device fromtransmitting the one of the N packets to the target access point.

In still other features, the N packets are transmitted to the firstaccess point prior to the handover of the service request device fromthe first access point to the target access point. In other features,the one of the N packets is received from the service request deviceprior to the control message being transmitted by the transceiver. Thecontrol message indicates reception of a redundant packet by thetransceiver based on the reception of the one of the N packets from theservice request device.

In yet other features, the N packets include a first packet and a secondpacket. The control message indicates reception of one of the firstpacket and the second packet by the first access point. The controlmessage is transmitted to the service request device to prevent theservice request device from transmitting the other one of the firstpacket and the second packet to the transceiver based on the controlmessage.

In other features, the first access point receives the one of the Npackets in a first radio access network and the transceiver receives theone of the N packets in a second radio access network. In otherfeatures, the control message is at least one of initially generatedwithin a packet data convergence protocol layer of the transceiver andinitially generated as a packet data convergence protocol layer controlpacket data unit.

In other features, the control message indicates reception of M of the Npackets by the transceiver. M is an integer. The service request devicediscards the M of the N packets based on the control message. In otherfeatures, the one of the N packets is received from the service requestdevice based on reception of an acknowledgement signal by the servicerequest device from the first access point.

In yet other features, a network device is provided and includestransceiving means for transmitting N packets to a first access pointand for receiving a control message from a second access point. Thecontrol message indicates reception of one of the N packets by thesecond access point from the first access point during a handover of thenetwork device from the first access point to the second access point. Nis an integer. Control means causes the transceiving means to refrainfrom transmitting the one of the N packets to the second access pointbased on the control message. The handover of the network device fromthe first access point to the second access point occurs prior to thecontrol message being received by the transceiving means.

In still other features, the transceiving means transmits the one of theN packets to the second access point prior to the control message beingreceived by the transceiving means. The control message indicatesreception of a redundant packet by the second access point based onreception of the one of the N packets by the second access point.

In other features, the N packets include a first packet and a secondpacket. The control message indicates reception of one of the firstpacket and the second packet by the first access point. The controlmeans causes the transceiving means to refrain from transmitting theother one of the first packet and the second packet to the second accesspoint based on the control message.

In yet other features, the first access point receives the one of the Npackets in a first radio access network and the second access pointreceives the one of the N packets in a second radio access network. Inother features, the control message is at least one of initiallygenerated within a packet data convergence protocol layer of the secondaccess point and initially generated as a packet data convergenceprotocol layer control packet data unit.

In other features, the transceiving means transmits a first set ofservice data units to the first access point. The first set of servicedata units includes the N packets. The transceiving means transmits asecond set of service data units to the second access point. The secondset of service data units including the one of the N packets.

In still other features, the transceiving means receives the controlmessage prior to transmitting the one of the N packets to the secondaccess point. In other features, the transceiving means receives thecontrol message prior to transmitting the N packets to the second accesspoint. The control means causes the transceiving means to refrain fromtransmitting the N packets to the second access point based on thecontrol message.

In other features, the control message indicates reception of M of the Npackets. M is an integer. The control means causes the transceivingmeans to refrain from transmitting the M of the N packets to the secondaccess point.

In other features, the transceiving means transmits the one of the Npackets to the second access point based on reception of anacknowledgement signal from the first access point. In other features,the transceiving means discards at least one of the N packets after apredetermined period. In other features, the transceiving meanstransmits the one of the N packets to the second access point based onexpiration of a predetermined time period.

In other features, a target access point is provided and includestransceiving means for receiving one of N packets associated with aservice request device. The one of the N packets is received by thetransceiving means from a first access point during a handover of theservice request device from the first access point to the target accesspoint. The N packets are transmitted from the service request device tothe first access point and N is an integer. Control means for generatinga control message. The control message indicates reception of the one ofthe N packets by the transceiving means. The transceiving meanstransmits the control message to the service request device to preventthe service request device from transmitting the one of the N packets tothe target access point.

In other features, the service request device transmits the N packets tothe first access point prior to the handover of the service requestdevice from the first access point to the target access point. In stillother features, the transceiving means receives the one of the N packetsfrom the service request device prior to the control message beingtransmitted by the transceiving means. The control message indicatesreception of a redundant packet by the transceiving means based on thereception of the one of the N packets from the service request device.

In other features, the N packets include a first packet and a secondpacket. The control message indicates reception of one of the firstpacket and the second packet by the first access point. The controlmeans causes the transceiving means to transmit the control message tothe service request device. This prevents the service request devicefrom transmitting the other one of the first packet and the secondpacket to the transceiving means based on the control message.

In other features, the first access point receives the one of the Npackets in a first radio access network and the transceiving meansreceives the one of the N packets in a second radio access network. Inyet other features, the control message is at least one of initiallygenerated within a packet data convergence protocol layer of thetransceiving means and initially generated as a packet data convergenceprotocol layer control packet data unit.

In other features, the control message indicates reception of M of the Npackets by the transceiving means. M is an integer. The service requestdevice discards the M of the N packets based on the control message. Inother features, the transceiving means receives the one of the N packetsfrom the service request device based on reception of an acknowledgementsignal by the service request device from the first access point.

In still other features, the systems and methods described above areimplemented by a computer program including instructions that areexecutable by one or more processors. The computer program can reside(or be tangibly stored) on a computer readable medium such as but notlimited to memory, nonvolatile data storage, and/or other suitabletangible storage mediums.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, areintended for purposes of illustration only and are not intended to limitthe scope of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a functional block diagram illustrating a handover in anexemplary network system in accordance with the present disclosure;

FIG. 2 is a functional block diagram illustrating a handover in anotherexemplary network system in accordance with the present disclosure;

FIG. 3 is a functional block diagram illustrating a handover in anotherexemplary network system incorporating access points that each havemultiple transceivers in accordance with the present disclosure;

FIG. 4 is a functional block diagram illustrating a handover in anotherexemplary network system incorporating access points that each havemultiple protocol stacks in accordance with the present disclosure;

FIG. 5 is a functional block diagram illustrating a handover in anotherexemplary network system incorporating access points that each have asingle transceiver in accordance with the present disclosure;

FIGS. 6A and 6B illustrate a method of operating a network system duringa handover in accordance with the present disclosure;

FIG. 7 is a functional block diagram of an exemplary network system inaccordance with the present disclosure;

FIG. 8 is a functional block diagram of an exemplary network systemillustrating non-roaming access via a radio access network in accordancewith the present disclosure;

FIG. 9 is a functional block diagram of an exemplary network systemillustrating roaming access via a radio access network in accordancewith the present disclosure;

FIG. 10A is a functional block diagram of a vehicle control system;

FIG. 10B is a functional block diagram of a cellular phone; and

FIG. 10C is a functional block diagram of a mobile device.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is in no wayintended to limit the disclosure, its application, or uses. For purposesof clarity, the same reference numbers will be used in the drawings toidentify similar elements. As used herein, the phrase at least one of A,B, and C should be construed to mean a logical (A or B or C), using anon-exclusive logical or. It should be understood that steps within amethod may be executed in different order without altering theprinciples of the present disclosure.

As used herein, the term module refers to an Application SpecificIntegrated Circuit (ASIC), an electronic circuit, a processor (shared,dedicated, or group) and memory that execute one or more software orfirmware programs, a combinational logic circuit, and/or other suitablecomponents that provide the described functionality.

In the following description, a service request device (SRD) may referto user equipment (UE) and/or a mobile node. A service request devicemay include equipment of an end user, such as a processor, a radiointerface adaptor, etc. A service request device may include a mobilenetwork device, a personal data assistant (PDA), a computer, etc.

Also, in the following description, the term mobility protocol mayinclude a local mobility protocol and/or a global mobility protocol. Alocal mobility protocol may refer to a communication protocol used formobility by a service request device between access points of a network,such as a public land mobile network (PLMN). The access points are incommunication with different access routers. A global mobility protocolrefers to a communication protocol used for mobility by a servicerequest device between access points of different networks. Thedifferent networks may be different PLMNs.

A mobility protocol may include a mobile Internet protocol (MIP), whichmay refer to a host-based Internet protocol (IP) or a network-based IP.Internet Engineering Task Force (IETF) RFC 3344 and IETF RFC 3775 areincorporated herein by reference in their entirety. A host-based IP mayinclude a client mobile IP (CMIP), such as CMIPv4 and CMIPv6, or a dualstack mobile IP (DSMIP). A host-based IP is used when mobilitymanagement is handled by a service request device. A network-based IPmay include a proxy MIP (PMIP), such as PMIPv4 and PMIPv6. Anetwork-based IP may be used, for example, when mobility management ishandled by a mobility management entity (MME) or other network device onbehalf of a service request device.

In addition, in the following description various networks and networkdevices are disclosed. Although a particular number of each networkdevice is shown, any number of each network device may be included. Forexample, in a home network and/or a visited network, any number ofwireless access gateways (WAGs), home subscriber servers (HSSs),authentication authorization and accounting (AAA) servers, and so on maybe included. Selection of one of each of the devices may be performedduring communication with a service request device. Each of the networkdevices may be considered a remote network device relative to anothernetwork device.

The following network systems disclosed in FIGS. 1-5 and 7-9 may include3GPPTM system networks and/or LTE network systems and comply with 3GPPTMsystem technical specifications, some of which are stated herein.

Referring now to FIG. 1, an exemplary network system 10 is shown. Thenetwork system 10 includes a service request device 12, a first accesspoint 14 (first access point), and a second access point (target accesspoint) 16. The first access point 14 is located in a first radio accessnetwork (RAN) 18 and the second access point 16 is located in a secondRAN 20.

The service request device 12 may include a SRD control module 22, whichmay request various real-time and non-real-time services, such as Webbrowsing, voice over Internet phone (VoIP), electronic mail (email),file transfer protocol (ftp) applications, and real-time IP multimedia,as well as conversational and streaming services. The real-time andnon-real-time services may be provided by the first and second RANs. Theservice request device 12 is shown as accessing the first access point14 (designated 12 with SRD control module 22) and as accessing thesecond access point 16 (designated 12′ with SRD control module 22′).

The access points 14, 16 may each include an access point control module24, 26. The access points 14, 16, for example, may be base stations,such as evolved node B base stations (eNodeBs). The access points 14, 16may include one or more home agents, such as routers. The access points14, 16 may comply with one or more IEEE standards, such as 802.11,802.11a, 802.11b, 802.11g, 802.11h, 802.11n, 802.16, and 802.20, whichare incorporated herein by reference in their entirety.

The RANs 18, 20 may be cellular networks, LTE RANs, or other wirelessaccess networks, some of which are disclosed below. The RANs 18, 20 mayinclude 3GPPTM system networks, a visited public land mobile network(VPLMN), a home PLMN (HPLMN), etc. The RANs 18, 20 may comply with [1],[2], TS 22.278 “3GPPTM Service requirements for the evolved packetsystem (EPS)”, TS 23.060 “General Packet Radio Service (GPRS) servicedescription”, which are incorporated herein by reference in theirentirety.

During operation, the service request device 12 may move or roam betweenthe RANs 18, 20 without losing connection. When the service requestdevice 12 is at the out boundary or edge of the first RAN 18, a handovermay be performed to maintain a predetermined quality of service levelfor the service request device 12. This handover may occur whencommunication between the first access point 14 and the service requestdevice 12 begins to degrade, such as near the edge of the first RAN 18.For example, signals transmitted between the first access point 14 andthe service request device 12 may decrease in quality, a signal-to-noiseratio of communication signals may decrease, transmitted packets may notbe received or may be received with errors, etc.

During a handover, the first access point 14 in the first RAN 18 (firstnetwork) may transfer various information pertaining to the servicerequest device 12 to the second access point 16 in the second RAN(target network). The information may include, for example, connectioninformation and packet information. The connection information allowsthe service request device 12 to transfer between networks withoutlosing a connection. The connection information may include protocolinformation, address information, Internet protocol (IP) information,gateway information, account information, etc. The packet informationmay indicate packets most recently received by the first RAN 18, statusof a current message window, etc. The message window is associated witha current set of packets being transmitted.

When the service request device 12 switches between different networks,a host-based system or a network-based system may be used to establish aconnectivity tunnel and/or a mobility tunnel. The connectivity tunnelmay be a secured IP tunnel.

The host-based system may utilize CMIP or DSMIP protocols. CMIP versions4 and 6 are described in IP mobility request for support memos RFC 3344and in RFC 3775, which are incorporated herein by reference in theirentirety. DSMIPv6 is described in “Mobile IPv6 support for dual stack,Hosts, and Routers (DSMIPv6)” of an Internet draft by the IPv6 workinggroup of IETF, which is incorporated herein by reference in itsentirety. The network-based system may utilize PMIP protocols. PMIPversion 4 is described in an Internet-Draft titled “Mobility Managementusing Proxy Mobile IPv4” by Leung et al. and PMIPv6 is described in“Localized Mobility Management using Proxy Mobile IPv6” by Gundavelli,which are incorporated herein by reference in their entirety.

When a host-based protocol associated with version 4 networks, such asCMIPv4, is used, a serving gateway may function as a foreign agent (FA)and provide routing services to the service request device 12. This mayoccur when the service request device 12 is registered with a packetdata network (PDN) gateway. The PDN gateway performs as a home agent.The service request device 12 may receive IP configuration informationcontained in an agent advertisement message through CMIPv4 or link layerprotocols.

When a host-based protocol associated with a version 6 network, such asCMIPv6, is used, a serving gateway may function as an access router andprovide routing services to the service request device 12. The PDNgateway performs as a home agent. The service request device 12 mayreceive IP configuration information contained in a CMIPv6 routeradvertisement message through CMIPv6 or link layer protocols.

When a network-based protocol is used, a serving gateway may function asa PMIP client (i.e., a PMIP agent (PMA)). The PDN gateway performs as aPMIP home agent. A PMIP client allocates a SRD IP address and providesthe SRD IP address to the service request device 12. The PMIP clientperforms PMIP mobility procedures.

In operation, packets are transmitted and received between the servicerequest device 12 and the access points 14, 16. Acknowledgement (ACK)signals are transmitted upon successful reception of the packets. Forexample, when the service request device 12 transmits a packet to thefirst access point 14, the first access point 14 responds by sending anACK signal to the service request device 12 to indicate that the packetwas successfully received. The service request device 12 may thenrefrain from transmitting the packets to the access points 14, 16 andmay discard the packets.

During a handover and due to deteriorated communication between theservice request device 12 and the first access point 14, the servicerequest device 12 may not receive an ACK signal from the first accesspoint 14. This may occur when the first access point 14 successfullyreceives the transmitted packets. For this reason, the service requestdevice 12 may retransmit all of the previously transmitted packets tothe second access point 16. To prevent and/or minimize retransmission ofthe packets that have been successfully received, the second accesspoint 16 generates a control message. The control message is transmittedto the service request device 12 and indicates which packets have beensuccessfully received. The service request device 12 ceases transmissionof packets that have already been successfully received by the secondaccess point 16. This is described in further detail below.

Packets may be discarded for various reasons. Packets may be discardedafter a predetermined period, after a certain number of transmissionattempts, based on a connection with a target device, etc. Packets maybe discarded after they have been successfully received or when theyhave been unsuccessfully transmitted and/or received. The discardtechniques utilized by the service request device 12 apply to bothreal-time and non-real time applications.

The service request device 12 may perform a timer-based discard methodand a message-based discard method. The timer-based discard method mayrefer to the discarding of packets after a predetermined period. Forexample, the service request device 12 generates and attempts totransmit packets to the access points 14, 16. If the access points 14,16 do not respond with an ACK signal within the predetermined period,the service request device 12 may discard the packets. A firstmessage-based discard method may include the generation of the controlmessage, for example, by the second access point 16. The service requestdevice 12 may discard the packets upon reception of the control message.

Another message-based technique includes the transmission of a discardsignal (message), for example, by the service request device 12 to thesecond access point 16. The discard signal may indicate that the servicerequest device 12 has transmitted certain packets to the second accesspoint and that the packets are to be discarded. The message windowsignal may be generated regardless of whether the packets were receivedsuccessfully. The discard signal may also include a request to adjust amessage window.

Referring now to FIG. 2, another exemplary network system 50 is shown.The network system 50 includes a service request device 52, a firstaccess point 54, and a second access point 56. The first access point 54is located in a first RAN and the second access point 56 is located in asecond RAN. The service request device 52 is shown as accessing thefirst access point 54 (designated 52 with devices 60-74) and asaccessing the second access point 56 (designated 52′ with devices60′-74′).

The service request device 52 includes a protocol stack 60 that includesa physical (PHY) layer 62, a medium access control (MAC) sub-layer 64, aradio link control (RLC) sub-layer 66, and a packet data convergenceprotocol (PDCP) sub-layer 68. The PHY layer 62 may be referred to as aL1 layer. The MAC and the RLC sub-layers 64, 66 are associated with adata link layer (L2) and the PDCP sub-layer 68 is associated with anetwork layer (L3). In general, the PDCP sub-layer 68 is considered anupper layer to the RLC sub-layer 66. The RLC sub-layer 66 is consideredan upper layer to the MAC sub-layer 64. The MAC sub-layer 64 isconsidered an upper layer to the PHY layer 62. The functions of the PHYlayer 62, the MAC sub-layer 64, the RLC sub-layer 66 and the PDCPsub-layer 68 may include functions described in, for example, the RadioInterface Protocol Architecture 3GPP TS 25.301, which is incorporatedherein by reference in its entirety.

The PHY layer 62 provides information transfer services to the MACsub-layer 64 and other upper layers. The PHY layer 62 providesmacrodiversity distribution and combining and soft handover execution,error detection, encoding/decoding, multiplexing, frequency and timesynchronization, RF processing, etc. The MAC sub-layer 64 provides datatransfer including unacknowledged transfer of MAC SDUs. The MACsub-layer 64 also provides reallocation of radio resources, changes ofMAC parameters, mapping between logical channels and transport channels,selection of transport formats, priority handling, etc.

The RLC sub-layer 66 includes a RLC control module 70 and providesautomatic repeat request (ARQ) functionality coupled with radiotransmission. The RLC sub-layer 66 at the transmitting side retransmitsa failed packet based on ARQ positive ACK signal or negative ACK (NACK)feedback signal from the RLC sub-layer 66 at the receiving side. The RLCsub-layer 66 has multiple operating modes including a transparent mode(TM), an unacknowledged mode (UM), and an acknowledged mode (AM). TheRLC sub-layer 66 provides transparent data transfer of upper layer PDUs,unacknowledged data transfer of upper layer PDUs, and acknowledged datatransfer of upper layer PDUs. The RLC sub-layer 66 provides segmentationand reassembly, concatenation, transfer of user data, flow control,sequence number checking, SDU discarding, etc.

Sequence number checking is used in unacknowledged mode (UM) and assuresthe integrity of reassembled SDUs. Sequence number checking also allowsfor the detection of corrupted RLC SDUs through checking sequencenumbers in RLC PDUs when they are reassembled into a RLC SDU. RLC SDUdiscard is used to discharge a RLC SDU from a buffer. The RLC sub-layer66 informs a higher layer of discarded packets, (i.e., discarded RLCSDU). This may occur if the RLC SDU is discarded at the RLC sub-layer 66due to RLC re-establishment, a RLC reset, or an expiration of a timer inthe RLC sub-layer 66. The RLC sub-layer also informs the higher layer of“unrecoverable error” if the RLC sub-layer in the transmitting sideexhausts the maximum number of transmissions for the packet.

The PDCP sub-layer 68 includes a PDCP control module 72 and providesPDCP SDU delivery. The PDCP sub-layer 68 may provide header compressionand decompression, transfer of user data, PDCP SDU discard, etc. PDCPSDU discard is used to discharge a PDCP SDU from a buffer. The PDCPsub-layer 68 may include one or more discard timer(s) 74. Each of thediscard timer(s) 74 may be used in association with the transmission andsuccessful reception of one or more packet(s). The PDCP sub-layer 68 mayoperate in timer-based and/or message-based modes, which correspond withthe timer-based and message based techniques described herein.

The first access point 54 and the second access point 56 includerespective control modules 80, 82 with transceivers 84, 86. Thetransceivers 84, 86 are used to communicate with each other and with theservice request device 52. When communicating with each other, thetransceivers 84, 86 may communicate over an IP network 90. Thetransceivers 84, 86 may communicate using an asynchronous transfer mode(ATM), an orthogonal frequency-division multiplexing (OFDM) transfermode, Internet protocols, etc. The communication between thetransceivers 84, 86 may be wireless or wired. Each of the transceivers84, 86 may include one or more protocol stacks, as shown in FIGS. 3-5.One of the protocol stacks may be used for wireless communication withthe service request device 52.

Referring now to FIG. 3, another exemplary network system 100 is shown.The network system 100 includes a service request device 102, a firstaccess point 104, and a second access point 106. The first access point104 is located in a first RAN and the second access point 106 is locatedin a second RAN.

The service request device 102 includes a first protocol stack 108 thatincludes a SRD PHY layer 110, a SRD MAC sub-layer 112, a SRD RLCsub-layer 114, and a SRD PDCP sub-layer 116. The SRD RLC sub-layer 114and the SRD PDCP sub-layer 116 respectively include a SRD RLC controlmodule 118 and a SRD PDCP control module 120. The service request device102 is shown as accessing the first access point 104 (designated 102with devices 108-120) and as accessing the second access point 106(designated 102′ with devices 108′-120′).

The access points 104, 106 include respective IP and radio controlmodules 130, 132, 134, 136. The IP control modules 130, 132 are used forcommunication between the access points 104, 106, which may be via an IPnetwork 140. The IP control modules 130, 132 may communicate with eachother via IP transceivers 137, 139 using wired or wireless communicationtechniques. The radio control modules 134, 136 include radiotransceivers 138, 140 that are used for wireless communication with theservice request device 102. The radio transceivers 138, 140 includeprotocol stacks 142, 144 that have PHY layers 146, 148, MAC sub-layers150, 152, RLC sub-layers 154, 156, and PDCP sub-layers 158, 160. The RLCsub-layers 154, 156 and the PDCP sub-layers 158, 160 respectivelyinclude RLC control modules 162, 164 and PDCP control modules 166, 168.The IP transceivers may operate in an ATM or in an IP transfer mode. Theprotocol stacks operate in an OFDM transfer mode.

The layers 146-160 may have similar functions as and communicate withthe layers 110-116. The second PDCP sub-layer 160 may generate controlmessages, which are transmitted to the service request device 102 forindication of packets received from the first AP 104 and/or the firstPDCP sub-layer 158.

Referring now to FIG. 4, another exemplary network system 150 is shown.The network system 150 includes a service request device 152, a firstaccess point 154, and a second access point 156. The first access point154 is located in a first RAN and the second access point 156 is locatedin a second RAN. The service request device 152 is shown as accessingthe first access point 154 (designated 152) and as accessing the secondaccess point 156 (designated 152′).

The first access point 154 and the second access point 156 respectivelyinclude IP transceivers 160, 162 with first protocol stacks 164, 166 andradio transceivers 168, 170 with second protocol stacks 172, 174. Thefirst protocol stacks 164, 166 are used for communication with eachother, which may be via an IP network 180. The second protocol stacks172, 174 are used for communication with the service request device 152.The first protocol stacks 164, 166 may be different than and/or includedifferent layers than the second protocol stacks 172, 174.

Referring now to FIG. 5, another exemplary network system 180 is shown.The network system 180 includes a service request device 182, a firstaccess point 184, and a second access point 186. The first access point184 is located in a first RAN and the second access point 186 is locatedin a second RAN. The service request device 182 is shown as accessingthe first access point 184 (designated 182) and as accessing the secondaccess point 186 (designated 182′).

The first access point 184 and the second access point 186 includerespective transceivers 188, 190 with protocol stacks 192, 194. Theprotocol stacks 192, 194 are used for communication between the accesspoints 184, 186 and for communication with the service request device182. The communication between the access points 184, 186 is wirelessand may be via an IP network 192. The communication between the accesspoints 184, 186 may not be via the IP network 192. For example, thefirst access point 184 may communicate directly with the second accesspoint 186, via a gateway, or via an intermediate communication node.

Referring now to FIGS. 6A-B, a method of operating a network systemduring a handover is shown. The method may be applied to the networksystems disclosed herein including the network systems of FIGS. 1-5 and7-9. The method may begin at step 300.

In step 302, a first access point communicates with a service requestdevice. The service request device transmits packets (originallytransmitted packets) to the first access point. For example, the servicerequest device may transmit to the first access point packets X₁-X₄.

In step 304, the first access point detects that a communication link orsignal between the first access point and the service request device isdeteriorating. In step 306, the first access point transmits a radiomeasurement request signal to the service request device.

In step 308, the service request device initiates a radio measurementbased on the radio measurement request. The service request device maydetect neighboring access points of the first access point. The servicerequest device measures the radio strength of the neighboring accesspoints. For example, the service request device detects and measures theradio signal strength from a second access point. The signal strengthsmay be stored.

In step 310, the service request device transmits a report to the firstaccess point indicating the radio signal strength of the second accesspoint. In step 312, the first access point receives the report anddetermines that the radio signal strength for the service request devicewith the second access point is better (or stronger) than the radiosignal strength with the first access point.

In step 314, the first access point transmits a handover request signalto the second access point. The handover request includes informationpertaining to the service request device to allow the second accesspoint to determine if the second access point can support the servicerequest device. The handover request information may include protocolinformation, network information, subscriber information, etc.

In step 316, the second access point determines whether to accept theservice request device based on the handover request information. Whenthe second access point accepts the service request device, step 317 isperformed, otherwise step 320 is performed.

In step 317, the second access point may transmit an accept signal tothe first access point that indicates acceptance of the service requestdevice. In step 318, the first access point transmits a handover commandmessage to the service request device. The handover command messageinstructs the service request device to handover to the second accesspoint. The handover command message may include information that allowsthe service request device to do the handover, such as protocolinformation, network information, access point information, etc.

In step 320, the second access point may transmit a reject signalindicating that the second access point does not accept the servicerequest device. In step 322, control of the first access pointdetermines whether to generate another radio measurement request or toselect the next best access point based on the report of step 310. Whenanother radio measurement request is to be generated, control of thefirst access point returns to step 306. When another access point(updated access point) is to be selected control of the first accesspoint returns to step 312 based on the report of step 310. Steps 312-316may be repeated based on the updated access point rather than the secondaccess point.

In step 323, the first access point and/or the PDCP layer of the firstaccess point may generate a packet information signal, which may betransmitted to the PDCP layer of the second access point (or updatedaccess point). The packet information signal indicates to the secondaccess point which packets have been received by the first access pointfrom the service request device. The packet information signal mayidentify the packets, include the packets, and/or include a messagewindow that is associated with the packets.

For example, when the service request device transmits the packets X₁-X₄to the first access point, the first access point may successfullyreceive packets X₂ and X₄. The first access point provides packets X₂and X₄ to the second access point. The number of packets and the size ofthe message window may vary per application. The message window providesthe second access point with a point of reference as to which packetsare to be transmitted to the second access point by the service requestdevice. The message window may provide a starting sequence number and anending sequence number, which identify first and last packets.

Step 323 may be performed earlier or later on in this disclosed method.For example, step 323 may be performed before step 322 or after step324. The performance of step 323 before or during steps 324-328 allowsthe first access point to transmit the packet information signal to thesecond access point during the handover between the service requestdevice and the second access point. This allows the second access pointto be updated with respect to transmitted and received packets and to beready for communication with the service request device at the end ofstep 328. Also, as the second access point is updated with the packetinformation, the second access point may generate and transmit a controlmessage to the service request device, as performed in steps 330 and334.

In step 324, the service request device receives the handover commandmessage and initiates a handover to the second access point. In step326, the service request device acquires the second access point andsuccessfully completes the handover. The service request devicetransmits to the second access point a handover complete message.

In step 328, normal operation, i.e., packet transmission and receptionfor the service request device resumes with the second access pointinstead of the first access point. This operation may be altered basedon the reception of control messages from the second access point.

As a first option, steps 330-333 may be performed. As a second optionsteps 334-340 may be performed. The first and second options may beselected based on the capability of the second access point, how quickthe second access point is in transmitting a control message, and/or howproactive the second access point is in preventing transmission ofredundant packets. A second access point may perform the first and/orsecond options.

In step 330, the second access point may generate and transmit a controlmessage to the service request device. The control message may begenerated by a PDCP layer of the service request device and may bereferred to as a PDCP control packet data unit (PDU). The controlmessage indicates to the service request device which packets have beensuccessfully received. Before step 330 the service request device maynot have knowledge of packets successfully received by the first accesspoint due to not receiving an acknowledgement (ACK) signal from thefirst access point. Continuing from the above example, the controlmessage may indicate that the packets X₂ and X₄ were successfullyreceived and/or indicate that the packets X₁ and X₃ were notsuccessfully received. Step 330 may be performed before the servicerequest device transmits any redundant packets to the second accesspoint.

In step 331, the packets that have been received may be discarded by theservice request device. The packets may be discarded in step 331 or instep 342, as described below. In step 332, the service request devicedetermines whether one or more predetermined period(s) are expired withrespect to the originally transmitted packets. For example, the servicerequest device determines whether predetermined period(s) are expiredfor packets X₁-X₄. When the predetermined period(s) are expired, theservice request device proceeds to step 342 to adjust a message windowand discard one or more of the packets X₁-X₄. When the predeterminedperiod(s) are not expired, the service request device may proceed tostep 333. In step 333, the service request device may transmit theunsuccessfully received packets, for example, packets X₁ and X₃ to thesecond access point.

In step 334, the service request device begins transmitting theoriginally transmitted packets to the second access point. Theoriginally transmitted packets may be transmitted before the receptionof a control message from the second access point. For example, theservice request device may begin to transmit packets X₁-X₄ to the secondaccess point. The packets may be transmitted sequentially.

In step 336, the second access point detects a redundant packet. Forexample, the second access point may detect a redundant packet when thepacket X₂ is received. This is due to the reception of the packet X₂from the first access point and from the service request device by thesecond access point.

In step 338, the second access point may generate and transmit thecontrol message to the service request device. The control message maybe generated by a PDCP layer of the service request device and may bereferred to as a PDCP control PDU. The control message acknowledgesreceived packets. The control message indicates to the service requestdevice the packets that have been successfully received by the secondaccess point. The control message may be generated and transmitted afterreception of the first redundant packet and before the reception of oneor more other redundant packets. This minimizes the number of redundantpackets transmitted, improves packet transmission efficiency, radioresource usage, and minimizes the use of system resources for thetransmission of redundant packets.

In step 340, the service request device ceases to transmit redundantpackets based on the control message. The service request device mayreceive the control message and cease transmission of redundant packetsbefore transmission of all of the originally transmitted packets. Thepackets that have been received may be discarded by the service requestdevice. The packets may be discarded in step 340 or in step 342, asdescribed below.

In step 342, the service request device may generate and transmit amessage window signal to the second access point. The message windowsignal may indicate to the second access point that the service requestdevice has attempted to transmit certain packets to the second accesspoint and that the service request device is now going to discard thesepackets. The packets may be discarded regardless of whether the packetshave been successfully received by the second access point. The packets,such as RLC service data units (SDUs) or PDCP SDUs, may be discardedfrom the RLC or PDCP layers of the service request device. The secondaccess point may also discard corresponding packets to the discardedpackets of the service request device.

The message window signal and any response signals generated based onthe message window signal allow the service request device and thesecond access point to agree on a sequence number upon which to begintransmission of additional packets. When the packets to be discarded arein the RLC layer and/or assigned to a sequence number, a RLC discardtechnique may be used, such as a move receiving window (MRW) technique.An example MRW technique for a universal mobile telecommunication system(UMTS) is described in Radio Link Control Protocol Specification 3GPP TS25.322 and in European telecommunication standards institute (ETSI) TS125 322, which are incorporated herein by reference in their entirety.Control may end at 344.

The above-described steps in the above-described Figures are meant to beillustrative examples; the steps may be performed sequentially,synchronously, simultaneously, continuously, during overlapping timeperiods or in a different order depending upon the application.

The following FIGS. 7-9 provide additional example network systems inwhich the techniques of the present application may be applied.

Referring now to FIG. 7, an exemplary network system 400 is shown. Thenetwork system 400 includes a service request device 402 that maycommunicate with the Internet 404 and/or one or more remote networks406. The service request device 402 may communicate with a radio accessnetwork (RAN) 408, such as an evolved universal terrestrial radio accessnetwork (EUTRAN) of the remote networks 406 as indicated by signal line410 or may communicate with the remote networks 406 via an accessnetwork. Some examples of an access network are a wireless local areanetwork (WLAN) 412, a first cellular network 414, and a second cellularnetwork 416. The access points of the networks 412-416 may performhandovers with respect to the service request device 402 and generateradio measurement, handover requests, handover responses, handovercommand messages, control messages, PDCP control PDUs, etc., asdescribed above.

The network system 400 provides connectivity and/or mobility management.The connectivity management is provided in an efficient manner using oneor more of the techniques described herein. Mobility management allowsthe service request device 402 to move between local and/or globalnetworks. The mobility may be provided through establishment of Internetprotocol (IP) connectivity between the service request device 402 andthe remote networks 406.

The service request device 402 includes a service request control module420 that provides connectivity protocol information to the remotenetworks 406. The service request control module 420 may identify apacket data network (PDN) gateway, such as one of the PDN gateways 422,of the remote networks 406 to provide requested services. The servicerequest device 402 accesses packet switched domain services via theselected PDN gateway. The PDN gateway may be located in a home PLMN(HPLMN). The service request device 402 may request various real-timeand non-real-time services, such as Web browsing, voice over Internetphone (VoIP), electronic mail (email), and real-time IP multimedia, aswell as conversational and streaming services.

The remote networks 406 may include 3GPP™ system networks, a VPLMN, aHPLMN, etc. The remote networks 406 may comply with [1], [2], TS 22.278“3GPP™ Service requirements for the evolved packet system (EPS)”, TS23.060 “General Packet Radio Service (GPRS) service description”, whichare incorporated herein by reference in their entirety. The remotenetworks 406 may include the RAN 408, the PDN gateways 422, a MME 424,serving gateways 426, and remote servers 428, such as home subscriberservers (HSSs). The MME 424 may include a MME control module 430 thatsupports connectivity and/or mobility of the service request device 402.The serving gateways 426 may include system architecture evolution (SAE)gateways.

The remote servers 428 may include PDN records 432, DNS records 434, andSRD records 436. The PDN records 432 include information regarding theservices, connectivity protocols, and mobility protocols supported bythe PDN gateways 422. The DNS records 434 include information regardingthe services and connectivity protocols supported by packet datagateways (PDGs). The DNS records 434 may also include mobility protocolssupported by the PDGs. The SRD records 436 include information regardingthe subscriber and account associated with the service request device402.

Each of the PDN gateways 422 may have a physical address (effectiveaddress) and/or one or more logical addresses, which are referred to asremote IP addresses. Each remote IP address may have an associatedservice and connectivity and mobility protocol and be assigned to theservice request device 402. For example only, a remote IP address may beassociated with home-based IP CMIPv6 and be used to provide VoIP serviceto the service request device 402.

When the service request device 402 initially accesses the networksystem 400, the MME 424, the PDN gateways 422, the serving gateways 426,and the remote servers 428 are unaware of the SRD preferred PDN, PDNgateway, and IP services. The MME 424, the PDN gateways 413, the servinggateways 426 and the remote servers 428 may support multipleconnectivity protocols and services. The techniques described hereininclude the service request device 402 providing PDN, PDN gateway and IPservices information early on in an attachment process. This improvesnetwork performance and quickly provides the services desired by theservice request device.

The WLAN 412 includes a WLAN access point (AP) 440 with an AP controlmodule 442. The WLAN AP 440, for example, may be a base station, such asan evolved node B base station (eNodeB). The WLAN 440 may also includeone or more home agents 444, such as routers. The AP mobility controlmodule 442 facilitates authentication of the service request device 402and the transfer of connectivity protocol information, mobility protocolinformation, PDN information, PDN gateway information, and IP servicesinformation between the service request device 402 and network devicesof the remote networks. The WLAN 22 may comply with one or more IEEEstandards 802.11, 802.11a, 802.11b, 802.11g, 802.11h, 802.11n, 802.16,and 802.20, which are incorporated herein by reference in theirentirety.

The cellular networks 414, 416 may include a first cellular network AP446 and a second network AP 448 with respective AP control modules 450,452, as shown. The AP control modules 446, 448 may also facilitateauthentication of the service request device 402 and the transfer ofconnectivity and mobility protocol information, and PDN gatewayinformation between the service request device 402 and network devicesof the remote networks 406.

During operation, the service request device 402 may move or roambetween the networks 412, 414, 416 without losing connection to one ormore of the remote networks 406. When in communication with the RAN 408,IP traffic flows between the RAN 408 and the serving gateways 426. Whenin communication with the networks 412, 414, 416, IP traffic flowsbetween the networks 412, 414, 416 and the serving gateways 426.

When the service request device 402 accesses the remote networks 406while roaming between the networks 412, 414, 416, connectivity andmobility tunnels, may be used to manage and maintain connectivity andmobility of the service request device 402. When the service requestdevice 402 switches between different networks, a host-based system or anetwork-based system may be used to establish a connectivity tunneland/or a mobility tunnel. The connectivity tunnel may be a secured IPtunnel.

Referring now to FIG. 8, another exemplary network system illustratingnon-roaming access via a radio access network 501, such as a 3GPP™network, is shown. The network system 500 includes a service requestdevice 502 with an SRD control module 503 that obtains network access toreceive services, such as operator IP services 504, from a PDN 106. Theservice request device 502 establishes Internet protocol (IP)connectivity with a PDN gateway 508 to receive the services 504. Theservices 504 may include real-time and non-real-time services, such asWeb browsing, voice over Internet phone (VoIP), electronic mail (email),and IP multimedia subsystem (IMS) services, packet switched servicesequence (PSS) services, conversational and streaming services, etc. Theaccess points of the radio access networks of the network system mayperform handovers with respect to the service request device 502 andgenerate radio measurement, handover requests, handover responses,handover command messages, control messages, PDCP control PDUs, etc., asdescribed above.

The network system 500 may include the PDN gateway 508, an evolveduniversal terrestrial radio access network (EUTRAN) 510, a servinggateway 512, a mobility management entity (MME) 514, a servicing generalpacket radio service support node (SGSN) 516, and a home subscriberserver (HSS) 518. The SGSN 516 may be in communication with a GSM EDGERAN (GERAN) 517 and/or a universal terrestrial RAN (UTRAN) 519. TheUTRAN 519 may be the same as the EUTRAN 510 or may be another RAN. ThePDN gateway 508, the EUTRAN 510, the serving gateway 512, the MME 514,and the home subscriber server 518 respectively include a PDN gatewaycontrol module 520, a EUTRAN control module 522, a serving gatewaycontrol module 524, a MME control module 526, and a HSS control module528.

The PDN gateway 508 is in communication with a policy and changing rulesfunction (PCRF) entity 530 and the PDN 506. The PCRF entity 530 may beused to terminate reference points between network devices, such asreference points associated with the serving gateway 512 and the PCRFentity 530. Reference points refer to communication links betweennetwork devices.

The serving gateway 512 may be a SAE gateway or a wireless accessgateway (WAG). The MME 514 is in communication with each of the EUTRAN510, the serving gateway 512, the SGSN 116, and the HSS 518. The MME 514performs SRD tracking and security functions. The serving gateway 512 isin communication with the PDN gateway 508, the EUTRAN 510, and the SGSN516. The SGSN 516 may perform MME selection and/or serving gatewayselection.

The HSS 518 may have authentication and subscriber profile information,such as for a subscriber of the service request device 502, to accessthe PDN 506. The HSS 518, the MME 514, and/or the serving gateway 524may perform PDN, PDN gateway, and IP services selections. The selectionsmay be based on PDN, PDN gateway, and IP service information provided bythe service request device 502. For example only, the HSS 518 mayauthenticate the subscriber after an invoked tunnel establishmentrequest by the service request device 102.

Referring now to FIG. 9, another exemplary network system 550illustrating roaming access via a radio access network 551 is shown. Thenetwork system 150 includes a service request device 552 with an SRDcontrol module 553 that obtains network access to receive services, suchas operator IP services 554, from a PDN 556. The PDN 556 may be part ofa HPLMN, whereas the service request device 552 is located in a VPLMN.The service request device 552 establishes IP connectivity with a PDNgateway 558 to receive the services 554. The access points of the radioaccess networks of the network system 550 may perform handovers withrespect to the service request device 502 and generate radiomeasurement, handover requests, handover responses, handover commandmessages, control messages, PDCP control PDUs, etc., as described above.

The network system 550 may include the RAN 551, the PDN gateway 558, aserving gateway 562, a MME 564, a SGSN 566, and a HSS 568. The SGSN 566may be in communication with a GERAN 569 and/or an UTRAN 570. The UTRAN570 may be the same as the RAN 551 or may be another RAN. The PDNgateway 558, the RAN 551, the serving gateway 562, the MME 564, and thehome subscriber server 568 respectively include a PDN gateway controlmodule 572, a EUTRAN control module 574, a serving gateway controlmodule 576, a MME control module 578, and a HSS control module 580.

The PDN gateway 558 is in communication with a PCRF entity 582 and thePDN 556. The PCRF entity 582 may be used to terminate reference pointsbetween network devices, such as reference points associated with theserving gateway 562 and the PCRF entity 582.

The serving gateway 562 may be a SAE gateway or a wireless accessgateway (WAG). The MME 564 is in communication with each of the RAN 551,the serving gateway 562, the SGSN 566, and the HSS 568. The MME 564performs SRD tracking and security functions. The serving gateway 562 isin communication with the PDN gateway 558, the RAN 551, and the SGSN566. The SGSN 566 may perform MME selection and/or serving gatewayselection.

The HSS 568 may have authentication and subscriber profile information,such as for a subscriber of the service request device 552, to accessthe PDN 556. The HSS 568, the MME 564, and/or the serving gateway 5162may perform PDN, PDN gateway, and IP services selections. The selectionsmay be based on PDN, PDN gateway, and IP service information provided bythe service request device 552. For example only, the HSS 568 mayauthenticate the subscriber after an invoked tunnel establishmentrequest by the service request device 552.

Referring now to FIGS. 10A-10C, various exemplary implementationsincorporating the teachings of the present disclosure are shown.

Referring now to FIG. 10A, the teachings of the disclosure may beimplemented in a network interface 752 of a vehicle 746. The vehicle 746may include a vehicle control system 747, a power supply 748, memory749, a storage device 750, and the network interface 752. If the networkinterface 752 includes a wireless local area network interface, anantenna (not shown) may be included. The vehicle control system 747 maybe a powertrain control system, a body control system, an entertainmentcontrol system, an anti-lock braking system (ABS), a navigation system,a telematics system, a lane departure system, an adaptive cruise controlsystem, etc.

The vehicle control system 747 may communicate with one or more sensors754 and generate one or more output signals 756. The sensors 754 mayinclude temperature sensors, acceleration sensors, pressure sensors,rotational sensors, airflow sensors, etc. The output signals 756 maycontrol engine operating parameters, transmission operating parameters,suspension parameters, brake parameters, etc.

The power supply 748 provides power to the components of the vehicle746. The vehicle control system 747 may store data in memory 749 and/orthe storage device 750. Memory 749 may include random access memory(RAM) and/or nonvolatile memory. Nonvolatile memory may include anysuitable type of semiconductor or solid-state memory, such as flashmemory (including NAND and NOR flash memory), phase change memory,magnetic RAM, and multi-state memory, in which each memory cell has morethan two states. The storage device 750 may include an optical storagedrive, such as a DVD drive, and/or a hard disk drive (HDD). The vehiclecontrol system 747 may communicate externally using the networkinterface 752.

Referring now to FIG. 10B, the teachings of the disclosure can beimplemented in a cellular network interface 767 of a cellular phone 758.The cellular phone 758 includes a phone control module 760, a powersupply 762, memory 764, a storage device 766, and the cellular networkinterface 767. The cellular phone 758 may include a network interface768, a microphone 770, an audio output 772 such as a speaker and/oroutput jack, a display 774, and a user input device 776 such as a keypadand/or pointing device. If the network interface 768 includes a wirelesslocal area network interface, an antenna (not shown) may be included.

The phone control module 760 may receive input signals from the cellularnetwork interface 767, the network interface 768, the microphone 770,and/or the user input device 776. The phone control module 760 mayprocess signals, including encoding, decoding, filtering, and/orformatting, and generate output signals. The output signals may becommunicated to one or more of memory 764, the storage device 766, thecellular network interface 767, the network interface 768, and the audiooutput 772.

Memory 764 may include random access memory (RAM) and/or nonvolatilememory. Nonvolatile memory may include any suitable type ofsemiconductor or solid-state memory, such as flash memory (includingNAND and NOR flash memory), phase change memory, magnetic RAM, andmulti-state memory, in which each memory cell has more than two states.The storage device 766 may include an optical storage drive, such as aDVD drive, and/or a hard disk drive (HDD). The power supply 762 providespower to the components of the cellular phone 758.

Referring now to FIG. 10C, the teachings of the disclosure can beimplemented in a network interface 794 of a mobile device 789. Themobile device 789 may include a mobile device control module 790, apower supply 791, memory 792, a storage device 793, the networkinterface 794, and an external interface 799. If the network interface794 includes a wireless local area network interface, an antenna (notshown) may be included.

The mobile device control module 790 may receive input signals from thenetwork interface 794 and/or the external interface 799. The externalinterface 799 may include USB, infrared, and/or Ethernet. The inputsignals may include compressed audio and/or video, and may be compliantwith the MP3 format. Additionally, the mobile device control module 790may receive input from a user input 796 such as a keypad, touchpad, orindividual buttons. The mobile device control module 790 may processinput signals, including encoding, decoding, filtering, and/orformatting, and generate output signals.

The mobile device control module 790 may output audio signals to anaudio output 797 and video signals to a display 798. The audio output797 may include a speaker and/or an output jack. The display 798 maypresent a graphical user interface, which may include menus, icons, etc.The power supply 791 provides power to the components of the mobiledevice 789. Memory 792 may include random access memory (RAM) and/ornonvolatile memory.

Nonvolatile memory may include any suitable type of semiconductor orsolid-state memory, such as flash memory (including NAND and NOR flashmemory), phase change memory, magnetic RAM, and multi-state memory, inwhich each memory cell has more than two states. The storage device 793may include an optical storage drive, such as a DVD drive, and/or a harddisk drive (HDD). The mobile device may include a personal digitalassistant, a media player, a laptop computer, a gaming console, or othermobile computing device.

The broad teachings of the disclosure can be implemented in a variety offorms. Therefore, while this disclosure includes particular examples,the true scope of the disclosure should not be so limited since othermodifications will become apparent upon a study of the drawings, thespecification, and the following claims.

What is claimed is:
 1. A network device comprising: a transceiverconfigured to (i) transmit, from the network device to a first accesspoint, a first plurality of packets and a second plurality of packets,(ii) transmit a request signal to a second access point to perform ahandover of support for the network device from the first access pointto the second access point, and (iii) receive a control message from thesecond access point based on the request signal, wherein the transceiveris configured to receive the control message subsequent to transmittingthe first plurality of packets to the second access point, and thecontrol message indicates the second access point received, during thehandover, (i) the first plurality of packets from the first accesspoint, and (ii) one of the first plurality of packets from the networkdevice; and a control module configured to, based on the controlmessage, (i) refrain from transmitting the one of the first plurality ofpackets to the second access point, (ii) discard the first plurality ofpackets, and (iii) transmit the second plurality of packets to thesecond access point via the transceiver.
 2. The network device of claim1, wherein the control module is configured to, based on the controlmessage: determine successful transmission of the first plurality ofpackets from the first access point to the second access point;determine unsuccessful transmission of the second plurality of packetsfrom the first access point to the second access point; perform thediscarding of the first plurality of packets based on the successfultransmission of the first plurality of packets from the first accesspoint to the second access point; and perform the transmitting of thesecond plurality of packets to the second access point via thetransceiver based on the unsuccessful transmission of the secondplurality of packets from the first access point to the second accesspoint.
 3. The network device of claim 1, wherein the control module isconfigured to, based on the control message: determine redundanttransmission of the one of the first plurality of packets to the secondaccess point; and refrain from transmitting the one of the firstplurality of packets to the second access point based on the redundanttransmission of the one of the first plurality of packets to the secondaccess point.
 4. The network device of claim 1, wherein the transceiverreceived the control message subsequent to the handover of support forthe network device from the first access point to the second accesspoint.
 5. The network device of claim 1, wherein the control module isconfigured to, prior to a predetermined period expiring, perform (i) thediscarding of the first plurality of packets, and (ii) the transmittingof the second plurality of packets to the second access point via thetransceiver.
 6. The network device of claim 5, wherein: the controlmodule is configured to, in response to the predetermined periodexpiring, transmit a message signal to the second access point via thetransceiver; and the message signal indicates (i) the second pluralityof packets have been transmitted from the network device to the secondaccess point, and (ii) the network device is to discard the secondplurality of packets.
 7. The network device of claim 1, wherein thetransceiver is configured to transmit the one of the first plurality ofpackets to: the first access point in a first radio access network; andthe second access point in a second radio access network.
 8. The networkdevice of claim 1, wherein the transceiver is configured to transmit: afirst set of service data units to the first access point, wherein thefirst set of service data units include the first plurality of packetsand the second plurality of packets; and a second set of service dataunits to the second access point, wherein the second set of service dataunits include the second plurality of packets.
 9. The network device ofclaim 1, wherein: the transceiver is configured to transmit the secondplurality of packets to the second access point based on whether thetransceiver has received an acknowledgement signal from the first accesspoint; and the acknowledgement signal indicates the first access pointreceived the second plurality of packets from the network device. 10.The network device of claim 1, wherein: the transceiver is configured toconsecutively transmit a first packet, a second packet, a third packet,and a fourth packet from the network device to the first access point;the second packet is transmitted from the network device to the firstaccess point subsequent to the first packet; the third packet istransmitted from the network device to the first access point subsequentto the second packet; the fourth packet is transmitted from the networkdevice to the first access point subsequent to the third packet; thefirst plurality of packets include the first packet and the thirdpacket; and the second plurality of packets include the second packetand the fourth packet.
 11. A method comprising: transmitting, from anetwork device to a first access point, a first plurality of packets anda second plurality of packets; transmitting a request signal to a secondaccess point to perform a handover of support for the network devicefrom the first access point to the second access point; receiving acontrol message from the second access point based on the requestsignal, wherein the control message is received subsequent to the firstplurality of packets being transmitted to the second access point, andthe control message indicates the second access point received, duringthe handover, (i) the first plurality of packets from the first accesspoint, and (ii) one of the first plurality of packets from the networkdevice; and based on the control message, refraining from transmittingthe one of the first plurality of packets to the second access point,discarding the first plurality of packets, and transmitting the secondplurality of packets to the second access point.
 12. The method of claim11, further comprising, based on the control message: determiningsuccessful transmission of the first plurality of packets from the firstaccess point to the second access point; and determining unsuccessfultransmission of the second plurality of packets from the first accesspoint to the second access point, wherein the discarding of the firstplurality of packets is based on the successful transmission of thefirst plurality of packets from the first access point to the secondaccess point, and wherein the transmitting of the second plurality ofpackets to the second access point is based on the unsuccessfultransmission of the second plurality of packets from the first accesspoint to the second access point.
 13. The method of claim 11, furthercomprising, based on the control message: determining redundanttransmission of the one of the first plurality of packets to the secondaccess point; and refraining from transmitting the one of the firstplurality of packets to the second access point based on the redundanttransmission of the one of the first plurality of packets to the secondaccess point.
 14. The method of claim 11, wherein the network devicereceived the control message subsequent to the handover of support forthe network device from the first access point to the second accesspoint.
 15. The method of claim 11, wherein, prior to a predeterminedperiod expiring, (i) the first plurality of packets are discarded, and(ii) the second plurality of packets are transmitted from the networkdevice to the second access point.
 16. The method of claim 15, furthercomprising, in response to the predetermined period expiring,transmitting a message signal from the network device to the secondaccess point, wherein the message signal indicates (i) the secondplurality of packets have been transmitted from the network device tothe second access point, and (ii) the network device is to discard thesecond plurality of packets.
 17. The method of claim 11, furthercomprising transmitting the one of the first plurality of packets to:the first access point in a first radio access network; and the secondaccess point in a second radio access network.
 18. The method of claim11, further comprising transmitting: a first set of service data unitsto the first access point, wherein the first set of service data unitsinclude the first plurality of packets and the second plurality ofpackets; and a second set of service data units to the second accesspoint, wherein the second set of service data units include the secondplurality of packets.
 19. The method of claim 11, wherein: the secondplurality of packets are transmitted to the second access point based onwhether the network device has received an acknowledgement signal fromthe first access point; and the acknowledgement signal indicates thefirst access point received the second plurality of packets from thenetwork device.
 20. The method of claim 11, further comprisingconsecutively transmitting a first packet, a second packet, a thirdpacket, and a fourth packet from the network device to the first accesspoint, wherein: the second packet is transmitted from the network deviceto the first access point subsequent to the first packet; the thirdpacket is transmitted from the network device to the first access pointsubsequent to the second packet; the fourth packet is transmitted fromthe network device to the first access point subsequent to the thirdpacket; the first plurality of packets include the first packet and thethird packet; and the second plurality of packets include the secondpacket and the fourth packet.